The amazing progress of LEDs
vox.com
The amazing progress of LEDs
1–10 of 52 posts
Re: The amazing progress of LEDs
#2Certain things are cheap in the rich world that are expensive in the 3rd world. Sewage, electricity, and water are so cheap in the 1st world, that we don't think about the cost.
The first time I saw 100% adoption of compact fluorescents was in Cambodia. They pay $.40/KWhr. That is insanely expensive (unless you live in Germany).
Lighting technology disproportionally benefits the poor rather than than the rich. Anyone that works on it is my hero. My family bought power for $.04 KW/hr, so I could study at night.
Re: The amazing progress of LEDs
#3Exponential growth is awesome! However, I was curious about the maximum theoretical lumens per watt to determine when the growth will fall flat. A current LED bulb gives about 60 lumens per watt. While an ideal monochromatic light source could give 683.[1] So it looks like there is _only_ one order of magnitude left in efficiency gains.
Re: The amazing progress of LEDs
#4One problem with current popular LED bulbs:
They emit more blue light than incandescent bulbs [1]. If people light their households with LED lights at night, it might shift their circadian rhythms [2]. Screwed up circadian rhythms can have all sorts of negative health/productivity effects.
[1] http://www.designingwithleds.com/measuring-light-quality-phi... [2] https://justgetflux.com/research.html
Re: The amazing progress of LEDs
#5I'm genuinely curious whether new homes will start wiring lighting for DC to accommodate all these new LED bulbs? I just don't have a good sense whether its more efficient to transform AC to DC at a central hub in the home to distribute to all rooms, or more efficient to do it at the bulb itself.
Re: The amazing progress of LEDs
#6Related: "Drowning in Light" from a few weeks ago: http://nautil.us/issue/11/light/drowning-in-light https://news.ycombinator.com/item?id=8344769
It makes the compelling argument that people are addicted to light. "Tsao calculates that, as a result, light represents a constant fraction of per capita gross domestic product (GDP) over time; the world has been spending 0.72 percent of its GDP for light for 300 years now. If there are other energy markets that show a constant percentage of GDP expenditure over time, Tsao doesn’t know of them."
Re: The amazing progress of LEDs
#7One problem with current popular LED bulbs: They emit more blue light than incandescent bulbs [1]. If people light their households with LED lights at night, it might shift their circadian rhythms [2]. Screwed up circadian rhythms can have all sorts of negative health/productivity effects. [1] http://www.designingwithleds.com/measuring-light-quality-phi... [2] https://justgetflux.com/research.html
That thought occurred to me as well. Circadian phase delay already seems to be a problem re: the increasing brightness of our computing devices, almost all using LEDs.
New phones, tablets, TV's, etc. should come with a warning to keep them "dimmed down" in the evening, or better, keep use to a minimum late in the day. Sure, I know, the odds are about zilch people would actually heed such advice, but it ought to be out there anyway.
Another thing is the the relatively low CRI. For many purposes (industrial, medical, artistic) the spectral output of bright LEDs is far less than ideal. LEDs will probably get closer to "full-spectrum" over time, and no doubt will easily beat the discontinuous spectrum of fluorescent lamps.
LEDs now just need to get cheap enough, and really need to work with existing dimmer controllers.
Re: The amazing progress of LEDs
#8I'm genuinely curious whether new homes will start wiring lighting for DC to accommodate all these new LED bulbs? I just don't have a good sense whether its more efficient to transform AC to DC at a central hub in the home to distribute to all rooms, or more efficient to do it at the bulb itself.
Line losses through the cables are usually a killer with really low voltage DC (like 5V or 12V), so I think that AC would be more efficient there.
But some datacentres are using 48V DC now and then just piping that through a switching regulators in the servers instead of going from AC to DC. That could be workable.
Re: The amazing progress of LEDs
#9He makes some dubious efficiency claims. It's true the colored LEDs have always been pretty efficient, but that's no use lighting your home. White LEDs have surpassed incandescent bulbs but still have a way to go to reach flourescent tubes and the grand-daddy of efficiency - gas discharge lamps.
One (the?) reason for low power levels is they generate so much heat and are difficult to cool. LEDs are still primarily heaters - useful in the winter.
Re: The amazing progress of LEDs
#10Exponential growth is awesome! However, I was curious about the maximum theoretical lumens per watt to determine when the growth will fall flat. A current LED bulb gives about 60 lumens per watt. While an ideal monochromatic light source could give 683.[1] So it looks like there is _only_ one order of magnitude left in efficiency gains. 1: http://en.wikipedia.org/wiki/Luminous_efficacy
That 683 lumens per watt number is, as you say, for a monochromatic light. This is not useful for humans to see with[1]; the actual limit for human vision is about 300 lumens per watt[2]. That's an upper bound even ignoring losses, and some LEDs are around 70 now, so the remaining efficiency gains we can make seem limited to about 3x.
[1] http://www.cool.conservation-us.org/byorg/us-doe/color_quali...